It is known in plastic extruders which use moving mold tunnels that it is important to provide efficient cooling within the mold tunnel. This efficiency is required because a moving mold tunnel is relatively short in length compared to fixed extruders.
Corma Inc. of Toronto, Ontario, Canada has over the last few years developed different cooling methods to cool plastic pipe formed in a moving mold tunnel extruder. Some of these methods have involved the pushing of air from the downstream end of the mold tunnel in an upstream direction into the mold tunnel. Corma Inc. has avoided the moving of cooling air in a downstream direction to the mold tunnel because this would necessitate the cooling air passing through and undesirably cooling the actual die equipment. It would also heat the cooling air. This die equipment must stay in its heated condition to produce a proper flow of molten plastic through the die equipment to the mold tunnel.